[Python-Dev] Speeding up instance attribute access (original) (raw)

Guido van Rossum guido@python.org
Mon, 11 Feb 2002 10:31:33 -0500

Guido van Rossum <guido@python.org> writes:

> - We need fallbacks for various exceptional cases: I think assignment to class also needs to be considered. Therefore, it may be best if the member array is a separate block (not allocated with the instances).

Good point. When class is assigned and the new class has a different layout of the member array then the old, all instance variables must be moved from the member array into a temporary dict, and then from the temporary dict redistributed over the new member array. If you're lucky, the temporary dict is empty after that; otherwise, it becomes the overflow dict.

It might also be worthwhile to incorporate slots access into that scheme, to avoid having to find the member descriptor in the class dictionary.

slots are really allocated in the object, not in a separate memory block. But I agree it would be nice if they could somehow be integrated.

--Guido van Rossum (home page: http://www.python.org/~guido/)